[Coco] Fixing coco2 keyboard traces.

chris cralt at comcast.net
Sun Jul 22 16:02:20 EDT 2012


RadioShack carries that same pen in their stores (they seem to have  
more and more electronic stuff now) but its $20 and reading the  
package I have the same concerns about it working on something  
flexible. And the amount it holds seems very small so I don't know if  
one pen will do all 15 traces. It would be a $40 risk for a 16K CB  
coco :-/

If I can't come up with another way to shore up the traces I may try  
bringing the plug to the good traces. I could remove it off the board  
and extend it with normal jumper wires up to the keyboard.

On Jul 22, 2012, at 8:00 AM, Brendan Donahe wrote:

> I've fixed non-flexible PCBs using a conductive pen, such as this one:
> http://www.mcmelectronics.com/product/CAIG-LABORATORIES-CW100P-/ 
> 200-175
> I'm not sure if this would work for the flexible "ribbon" or not,  
> though.
> Brendan
> On Jul 21, 2012 10:12 PM, <cralt at comcast.net> wrote:
>> I saved a lowly 16K Coco2 non-ECB from a poll barn. It was in ruff  
>> shape
>> but I cleaned it up and got it working. The keyboard was totally  
>> full of
>> trash so i spend the morning dissembling it and washing each part  
>> off. It
>> all went back together good but only has a few keys working. I  
>> swapped
>> keyboards with another coco and verified it is the keyboard that is  
>> the
>> issue. The issue seems to be the ribbon that exits the keyboard. If I
>> bypass this with jumper clips I can get the keys to work. It seems  
>> the
>> resistance is higher on the traces on the exposed ribbon section  
>> then it is
>> on the traces that are in the keyboard. I can also see light  
>> through the
>> traces on the ribbon section.
>> I tried coloring over the tops of the traces with a #2 pencil but  
>> it didnt
>> help. It seems the coco wants to see zero ohms before it registers a
>> keystroke. Its only seeing 4-5 ohms through the bad traces.
>> Is there any way to rebuild the traces or some how attach jumper  
>> wires to
>> the membrane? I dont think I will be able to solder to them with out
>> melting the plastic. Any one have any tricks to fix this?
>> Thanks
>> -chris
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